Desktop

DesktopVirtualizationandEvolvingStrategiesforIT Service DeliveryJaime HalscottLesson 1: Why the Server Virtualization Model Doesn’t Work for VDIVirtualization is a topic that just about every IT professional has had at least some basicexposure to at this point. Many businesses have adopted some form of virtualinfrastructure, but this adoption is, at this time, mostly limited to server‐basedvirtualization. That isn’t to say that desktop virtualization is foreign, but it is emerging, andas such you may have very limited exposure to it.Server virtualization brought with it a host of justifications for projects, including serverconsolidation, decreased overall hardware costs, decreased support costs, simplifiedbackup, and many others. Do these hold true for desktop virtualization? We’ll explore thatanswer as we compare server and desktop virtualization. Let’s start with the planningphase.PlanningI’ve seen a lot of server virtualization projects succeed even with the worst planning upfront. The last server virtualization project I saw run into serious problems was the resultof a complete lack of planning. Even that one was salvaged and showed an immediatereturn on investment. My personal experience has shown that desktop virtualization is lesstolerant to planning missteps. This isn’t a bad thing per se.Every IT project should be planned from the start, and desktop virtualization is nodifferent. Building a plan that takes into account as many variables, goals, and metrics aspossible makes the project that much more likely to succeed.Desktop virtualization requires careful planning, testing, and piloting because it is soclosely tied to end user experience. Users will not tolerate slowdowns or peripherals thatdon’t work. Remember that you aren’t delivering just a desktop in desktop virtualization. Youare delivering a whole user experience.Server virtualization gives more wiggle room, if you will, in the project. Taking a singlephysical server and repurposing it to support multiple virtual servers doesn’t require acomplete restructuring of the network or additional hardware. Existing metrics forprocessor, memory, disk I/O, and such should already be in place on the physical server.These performance counters do a good job of showing approximate workloads for virtualservers over time. This data makes it relatively easy to pilot virtual server workloads.Desktops are different. Some users are more resource intensive than others and have lesstolerance for slowdowns. In general, the task of finding out this information isn’t easy.LicensingLicensing is also different. In many cases, server virtualization doesn’t require anyadditional operating system (OS) licensing. Most IT staff can rather quickly articulate whatthe Windows Server virtualization licensing rights are for the Standard, Enterprise, andDatacenter versions. The maturity of the server virtualization landscape has made thisinformation widely known in the course of a few years.3

DesktopVirtualizationandEvolvingStrategiesforIT Service DeliveryJaime HalscottThat said, I’m willing to bet that hardly as many readers will be able to explain withoutextensive research how many instances of Windows 7, for example, can be installed on aparticular VDI platform and how many can legally be run concurrently. There arealternative licensing schemes designed specifically for virtual desktops. Finding out howmuch a virtual license costs and the legal rights associated with that license remains adifficult task. This is part of a normal growing pain process with any technology. Vendorslike Microsoft have come up with several plans for desktop virtualization licensing, whichare meant to simplify and keep costs down—however, these plans still aren’t fully fleshedout.But before you can jump into licensing needs or even determining the key differencesbetween end users’ needs, you need to get back to the goals of the project. Let’s start byanalyzing the goals of desktop virtualization.The Goals of DesktopVirtualizationYou’ve probably started down this VDI path with the belief that the goals of desktopvirtualization are the same as those for server virtualization. Trying to start with a familiarknowledge base in server virtualization shouldn’t hurt a desktop virtualization project,should it? I think it might. Although some of the server virtualization goals apply directly todesktop virtualization, for most part, they don’t share the main business drivers.Understanding the differences is critical.Server virtualization is largely focused on driving up efficiency and driving down costs. Ittends to achieve these goals well. IT architects that take on server virtualization can drawmodels that show cost savings in a variety of ways:• Greater utilization of existing server hardware• Space savings in the data center• Reduced server maintenance costs• Reduced power and cooling costs• Software licensing savings• Reduced server deployment time• Application isolation• Multiple platforms on the same hardwareDesktop virtualization provides some of these benefits but not nearly as directly or in amanner that is as easy to quantify as server virtualization does. A desktop virtualizationsolution achieves a host of soft cost savings that requires a different analysis. These costsavings are going to be more difficult to quantify at the onset of the project than they arewith server virtualization. It doesn’t mean they aren’t just as beneficial, but rather that theyaren’t going to be immediately obvious.4